Talking TV: Time and space and the immortal Doctor Who

No other show in the history of television has journeyed as far and wide, as deep and high as the BBC's sci-fi classic "Doctor Who," which celebrates its 50th anniversary on Saturday.

Generations of fans have seen 11 incarnations of the Time Lord from Gallifrey hurtle through the heavens in his British police box-shaped TARDIS, saving countless lives and planets with his sonic screwdriver and general cleverness, and mourning those he could not. Monsters have bowed before him, as have queens both historical and fictitious. With a series of equally appealing companions, he has come to the aid of Charles Dickens, Vincent van Gogh, Agatha Christie and Winston Churchill. But in the end it is always the Doctor, alone, who captures our hearts, the lonely hero with the quick wit and sad smile on an endless quest to right all wrongs.

And his half-century birthday will not go unnoticed. BBC America has been running the second incarnation of the series, resurrected in 2005 by Russell T. Davies, nonstop. Friday night, "An Adventure in Space and Time," a docudrama about the making of the original series, debuts, a prelude to the international premiere on Saturday of "The Day of the Doctor," an anniversary special shrouded in secrecy and anticipation, that will reunite an unconfirmed number of Doctors, companions and nemeses and debut simultaneously in theaters and living rooms around the world.

On Thursday at noon, myself and fellow L.A. Times TV critic Robert Lloyd will join Times deputy social media director Stacey Leasca and maybe a superfan or two to discuss the mad and glorious universe of what is possibly the single most important television show ever made. So tweet your questions and comments (who's your favorite doctor/companion/enemy/episode?) to #asklatimes and join us as we explore the two-hearted Time Lord and all he has meant to us.